Apparatus for heat exchanging



July 7, 1931. F. E. KEY

APPARATUS FOR HEAT EXCHANGING Filed Oct. 31. 1927 7 Sheets-Sheet l all. an H 'n July 7, 1931. F. E. KEY 1,813,057

APPARATUS FOR HEAT EXCHANGING Filed Oct. 31, 1927 7 Sheets-Sheet 2 July 7, 1931. F. E. KEY 1,813,057

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APPARATUS FOR HEAT EXCHANGING Filed Oct. 31. 192 7 Sheets-Sheet 4 jufly 7, 39310 F. E. KEY 198139957 APPARATUS FOR HEAT EXCHANGING Filed Oct. 31, 1927 7 Sheets-Sheet 5 lull-.5

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APPARATUS FOR HEAT EXCHANGING Filed Oct. 31, 1927 7 Sheets-Sheet 7 Patented July 7, 1931 UNITED STATES PATENT OFFICE FREDERICK E. .KEY,OF EAST ST. LOUIS, ILLINOIS, ASSIGNOR TO KEY BOILER EQUIP- MENT (10., OF EAST ST. LOUIS, ILLINOIS, A. CORPORATION OF MISSOURI APPARATUS FOR HEAT EXCHANGING Application filed October 31, 1927. Serial No. 229,882.

My invention relates to improvements in apparatus for and method ofheat exchanging, and has for its primary object an apparatus whereby heat is exchanged from one fluid to another, the fluid to which the heat is exchanged being circulated in such a manner that a great amount of travel of the fluid to which the heat is exchanged is obtained.

A further object is to construct an apparatus for exchanging heat, such as is used in the cracking of oil in which the .oil to be cracked can travel at a high velocity of speed through the various tubes and still remain subjected to the heat for a long period of time.

A still further object is to construct a heat exchanger for heating fluids which is so constructed that while the fluid being heated remains subjected to the heat for a long pe- 2 riod of time, still the fluid is passed through the device at such a speed that should the fluid contain any substances which would be likely to be deposited on the walls of the tubes during the heating process, the speed of the fluid would eliminate this to a great extent. This makes my apparatus especially useful in the cracking of oil as it is a well known fact that the tubes, through which the oil passes while being heated for the crack- 0 ing process, become quickly obstructed by the deposit of what is called by the trade coke,

. it being a deposit of carbon'and other suspended matters which areseparated by the heat and deposited on the walls of the tubes thus gradually cutting down the capacity of these tubes as well as hindering the passage or exchange of heat therethrough. This necessitates frequent shutdowns so that the tubes can be cleaned out and where worms are used for this purpose, it is a very difficult matter to remove the accumulations therein.

A still further object is the method of heat 1 exchange in which a stream of fluid moves in one. direction for a predetermined distance and has a fluid core of substantially the same length, asthe' fluid-moving in the opposite direction. In this way, I obtain a stream which is substantially twice the length of the predetermined distance which either the q core or the surrounding stream travels.

Therefore, the fluid is subjected to the heat double the length of time than where a stream without a core is employed.

Another feature is that by my method, the fluld to be heated can be moved much more rapidly and heated much more thoroughly than where only a single stream is used and Fig. 3 is a section taken on the line 3-3- of Fig. 2;

Fig. 4 is an enlarged top plan View of one of the return bends made use of;

Fig. 5 is a vertical section of the same taken on the line 55 of Fig. 4;

Fig. 6 is an end view looking in the direction of the arrow 6 in Fig. 4;

Fig. 7 is a bottom plan View of the return bend;

Figs. 8, 9 and 10 are top plan views of various forms of return bends necessary in my device;

Fig. 11 is an enlarged elevation of the lock nut and bolt made use of;

Fig. 12 is atop plan view of the lock nut;

Fig. 13 is a side elevation of the core return bend employed;

Fig. 14 is an end view of the same;

Fig. 15 is an enlarged section of one set of tubes taken on the line l515 of Fig. 3;

Figs. 16 and 17 are. similar sections showing modified forms of construction for regulating the speed of the core and the main streamrj' i Fig. 18 is a vertical sectional view of a modified form of construction. of heat ex- "larfin horizontal plane and is designed to retional view with parts brokenaway illustrating the circulation of both fluid and heating I 'cured in the return bends.

agents;

Fig. 20 is a front View of Fig. 19 with the cap removed; 1

Fig.21 is a top plan View ofFig. 20;

Fig. 22 is an enlarged fragmental sectional view illustrating another manner of closing up the end of the tube which carries the main stream; and

Fig. 23 is a top plan view of the cap shown in Fig. 22.

In the construction of my deviceI employ a casing 25 which has its one end 26 closed in any suitable manner. The opposite end is preferably flanged as at 27. Surrounding the casing and to the rear of the flange 27 is a ring 28. This ring is provided with suitable openings to permit the passage of bolts 29. The bolts 29 extend through a head 30 and in order to make a leak-tight joint between the :head 30 and flange 27 a gasket 31 is employed.

This gasket may be of any suitable material according to the nature of the heating fluid employed. The head 30 is provided with aplurality of openings 32, the rear portions of which are counter-bored or enlarged as at 33.

Extending through the openings 32 are a plu rality of tubes 34. These tubes are closed at their rear end as indicated by the numeral 35, their. forward ends 36 extending into cylindrical openings 37 formed in the return bends 38. Before securing the ends 36 in the return bends the tubes are secured in the openings 32 by means of flue expanders or, if desired, they may be welded therein. The ends 36 of the tubes are also similarly se- It will be noted from Figs. 5 and 7 that eachof the return bends is arranged to re ceive a pair of tubes 34. The return bends are also provided with a passageway 39 through which fluid may pass from one of the tubes 34 to the other tube.

. Concentric with and in axialalignment 1 with the'openings 37 are formed tapered openings .or seats 40, which receive the tapered portions 41 of the return bends 42. These .return bends carry tubes 43, which tubes, when the return bends are in position, extend centrally and longitudinally of the tubes 34 but are of less len th than these tubes so that the ends 35 of the tubes 34 will be spaced some distance from the ends 44 of the tubes 43.

Extending upwardly from the return I bends 38 and integral therewith is a projection 45, which is substantially semi-circular and is provided near its top with a groove 46. This groove is also substantially semi-circuceive the nut 47 Through the nut extends a bolt 48, which has a reduced end 49. This reduced end fits in a depression 50 formed in the return bends 42. In this manner the tapered portions 41 of the return bends 42 are. tightly held in position in the tapered seats 40 but can be readily removed by releasing the bolt and then removing the nut 47.

'In Figs. 8, 9 and 10 I haveshown types of return bends slightly different than that disclosed in Figs. 4, 5, 6, and 7. These are necessary in order to get the continuous circulation of fluid and for the various posit ons the return bends 42 will assume in the assembly. This is clearly illustrated in Fig. 2. The general construction of these modified return bends, however, is the exception that the position of the pro ect1on 45 is slightly varie It will also be noted from Fig. 2 that one of'the return bends carries an inlet 51 andthe cooled heating medium. 58 represents supports between adjacent casings and 59 supports for the lowermost casing.

After the casings have been mounted as illustrated in Fig. 1 a supply pipe 60 is secured at one end to the inlet 51, its opposite end to a pump 61. This pump is for t e purpose of forcing the fluid through the various pipes at a predetermined rate of speed. 62

represents the. outlet pipe, which is secured at the outlet 52 and leads the heated flllld. to its final destination.

same with the The circulation of the fluids in the structure disclosed in Fig. 1 is fully disclosed in Fig. 3..

The fluid enters the inlet 51, passes in the direction of the arrows through the innerpipe 43 and out through the end 44 thereof into the pipe 34. Here, its direction is reversed and it flows back toward the head 30 I through the pipe 34 into the return bend 38. From there it goesthrough the passage 39 and enters the next pipe 34. In this pipe it flows toward the rear of the casing 25 ontoward the head 26. Then, it enters the open end 44 of the next pipe 43. Itthen passes forward through this pipe toward the head .30 into the return bend'38 where its direction is again reversed, flowin through the next pipe 33 towardthe rear 0 the casing. In this manner the fluid to be heated flows-alternately to the rear and front through the pipes 43 and alternately to the'front and rear through the pipes 34 thus traveling approximately twice the length of the pipes. This is continued until the fluid finally passes out through the outlet 52 where it enters a pipe 63, which pipe in turn is connected to the inlet 51 of an adjacent unit. It will be par ticularly noted from the construction that the cold fluid enters the unit which has the lowest temperature and as it becomes heated, rises and flows through an adjacent unit having a higher temperature. In this way I achieve a more equal exchange of heat because the fluid is gradually warmed by the gradually cooling heating medium and is sub-. jected to the greatest heat at the time when it is in the best condition to receive the same. This obviates undue chilling of the heating medium and assures the fluid being delivered from the heat exchanger at the highest possible temperature.

After the device has been in operation for a certain length of time, it is an easy matter to clean the same by merely removing the return bends 42 and withdrawing the tubes 43 when a flue brush or any cleaning means may be employed to clean out the tubes 34. The

tubes 43 can also be readily cleaned when withdrawn, and the whole assembly removed from the casing 25 by removing the nuts from the bolts 29 and removing the head 30.

In Figs. 18, 19 and 20 I show a construction which I call a multiple circulation. In this instance I employ a casing 70, one end of which is closed as indicated by the numeral 71. The opposite end of the'casing is fitted into a head 72 and is secured therein in any suitable manner, either by welding as indicated by the numeral 73 or otherwise. The head 72 is provided with walls 74 and 75 which are spaced apart so as to form a passage 76. This passage communicates with a port 77, the end of which is provided with a flange 78. This completes a unit and by means of the flange 78 several units can be secured together as illustrated in Fig. 18.

The casing has provided adjacent one end an outlet 79 and adjacent the opposite end an inlet 80 so that when several units are connected together a complete circulation of heating fluid can circulate from one unit to the other.

The wall 74 of the head is provided with openings 81 in which tubes 82 are secured at one end by expanding them similar to the manner of expanding flues in a flue sheet although, if desired, these tubes may be electrically welded therein. The ends 83 of the tubes are closed by any suitable means so that no fluid can escape therefrom. In other words, the tubes 82 have only one point of ingress or egress which is in the passageway 76. The wall is counter-bored as indicated by the numeral 84 for a predetermined distance, and concentric with the bores 84 are openings extending entirely through the wall 75 which are tapped as indicated by the numeral 85 so as to receive the bushings 86. These bushings carry tubes 87 which are of less diameter than the tubes 82 and have their ends 87' open. These ends are spaced from the closed ends 83 similarly to the ends 44 of the tubes 43.

Carried by certain of the tubes 82 are baflies 88, which extend in opposite directions so as to cause the heating agent to circulate around all of the tubes as illustrated in Fig. 19.

The head 72 is provided with a flange 89 through which bolts 90 extend so that the cap 91 can be secured thereto. This cap is provided with an inlet 92, which has a flange 93 to which a pipe 94 can be attached. The pipe 94 is secured in a flanged coupling 95 which is bolted to the flange 93 as illustrated in Fig. 18 and is for the purpose of completing suitable connections either to a pump or to a final delivery. By the construction last -mentioned and as disclosed in Fig. 18 the fluid to be heated is passed through the pipe 94 into the cap 91. From there it enters all of the pipes 87 simultaneously, passes therethrough to the rear of the pipe, then reverses itself, passing forward through the pipes 82 into the passage 76, then upward through the passage 77 and into the passage 76 of an adjacent unit where it enters the pipes 82 contained therein and reverses itself through the pipes 87, and then into the next cap from which it may be withdrawn in any suitable way and to any suitable storage place. By this construction instead of alternately having the fluid pass in one direction through the outer pipe and return in an opposite direction through the smaller pipe located within the outer pipe, the fluid in one unit passes in one'direction through all of the small pipes simultaneously and returns in the opposite direction through all of the outer pipes simultaneously. In this way a greater amount of fluid to be heated can be handled in a given unit of time although the heat imparted to the fluid will not be so great, but at the same time I will achieve the same result, which has been previously described, namely that a core of fluid to be heated Will travel in one direction while a surrounding shell or stream of fluid, which is being heated, will travel in the opposite direction so that the per foot of travel of fluid to be heated is doubled by my construction. It is also my intention with the last named modification to introduw the.

fluid to be heated at the point or into the unit from which the heating agent exhausts so that the fluid tobe heated will enter the coldest unit and as it gradually becomes heated progress toward the hotter units so that the heated fluid will leave the exchanger at the hottest point.

In Figs. 22 and 23 I have shown a modified form of closing the ends of the tubes 34 or 82. In this instance a sleeve 96 is employed in which the tubes are secured by rolling. This sleeve has an extension 97 which is similar to the extensions 45 on the heated, it is my opinion that the same will heating agent, and

return bends. The sleeve is provided with I 'a groove 98 in which the nut 99 is fitted simitapered so as to receive a cap 102, which cap is provided with a central depression 103 to receive the end 101 of the screw-100. The cap 102 is further provided with a lip 104, which is so positioned that when the screw 100 is loosened and the nut 99 removed a pinch bar can be inserted underneath the lip 104 for the removal of the cap 102.

My device can be used for oil cracking and also for heating fluids of any nature, whether liquid or gases, and as a heating medium I may use steam, either ordinary or superheated, hot gases of any kind, hot liquids, or a direct flame, and as previously mentioned I may connect the various units in series as disclosed in Fig. 3 or may connect them in multiple as in Fig. 19.

While I have shown a battery composed of only two units connected together and arranged one above the other, I do not desire to limit myself thereto as they may be arranged side by side or otherwise and any number of units may be interconnected. It will also be noted that the fluid to be heated enters each battery at the coldest part there of and gradually approaches the hotter part thereby preventing sudden chilling of the it is my belief that by gradually exchanging the heat, as before mentioned, I obtain a greater efliciency of heat exchange as well as reduce the strain set up by the expansion and contraction in the apparatus since all of the parts are more uniformly heated, and by this gradual progression of heat exchange the possibility of loosening joints is eliminated. It will. also be noted that by my construction the tubes can expand both laterally and longitudinally independently of each other, except in the case of the outer and inner tubes where they are secured in the return bends or in the heads but this portion of securing is so small as to not materially affect the general expansion and contraction.

It will also be noted that by my construction and method the exchange of heat will take place more readily because the outer tubes will become heated quickly. due to their intimate contact with the heating-agent and transfer their absorbed heat to the fluid there in, which fluid surrounds the core, or tubes which carry the core. This fluid will heat up the inner tubes, which in turn heat up the fluid core and afterthese tubes once become heated, they will readily transfer this heat to the fluid passing therethrough, and by splitting up longitudinally the fluid being become heated much more readily and thoroughly because it is divided into relatively a solid stream was employed.

By my construction as disclosed in Fig. 15

the rate of travel of the fluid through the tubes 34 and 43 is the same. In other words, the capacity of the tube 43 isexactly the same as the capacity of the space between it and the tube 34 when the two are inserted in each other. In Fig. 16 the capacity of the tube 43 is greater than the capacity of the space be- "ween the tubes 34 and 43. Consequently, the fluid passing through the tube 34 will have to move at a greater rate of speed than the fluid in the space around it, while in Fig. 17 the' reverse is true, the capacity of the space between the tubes 34 and 43 being greater than the capacity of the tube 43 and since the fluid is forced through these pipes,

it is obvious that if the capacity of the inner tube is equal to the capacity of the space betweenthe inner tube and the outer tube, the

fluid will flow in opposite directions at the same rate of speed, whereas if the capacity between the outer tube and the inner tube is less than the inner tube, the core will flow at a less rate of speed while if the capacity of the inner tube is less than the capacity of the space between the outer and inner tubes, the fluid will flow faster through the inner tube than through the space because it is my intention to force a certain amount of fluid per unit of time through these tubes. It will,

therefore, be seen that I can regulate the rate of flow of the core and of the surrounding stream to suit diflerent conditions without departing from the spirit of my invention.

' It will also 'be observed that by my apparatus and method that I have a constantly flowing stream of fluid, which is progressively heated from its introduction .into a heating medium at the coldest point of said medium till it reaches its exit at the hottest point of the medium and that the stream is divided into a core and an envelo which both travel throughout a predetermined distance in op-.

posite directions to each other, theenvelope receiving the heat by conduction directly from the heating medium and the core receiving its heat by conduction from the envelope.

It will also be noted that the core and envelope are intermingled at one point of their travel, thus in addition to the core receiving heat by conduction, it also receives heat by this intermingling. In this way I obtain an 2o,

extremely rapid exchange of heat and consequently reduce any sudden drop in temperature of the heating medium to a minimum.

In other words, I absorb practically all of the heat contained in the heating medium during the exchange and thereby increase the efliciency of my device.

While I have not shown any baflles in Fig. 3, I desire it to be understood that I may use baflles similar to those disclosed in Figs. 18 and 19 if found necessary or desirable.

Having fully described my invention, what I claim is 1. A heat exchanger comprising a casing closed at one end, a removable head for closmg the opposite end of said casing, a plurality of tubes projecting through said head into said casing, the ends of the tubes Within the casing being closed, means outside the casing for permitting communication between pairs of the tubes, tubes concentric with and Within the first-mentioned tubes, removable means for permitting communication between pairs of said last-mentioned tubes, whereby all the tubes are united to form a single sinuous passage, means for introducing a fluid into said tubes, and means through which a heating medium can enter and pass from said casing.

2 A heat exchanger comprising a casing closed at one end, a detachable head for closing the opposite end of said casing, tubes secured in and projecting through said head into said casing, the ends of said tubes Within the casing being closed, fixed return bends for connecting the opposite ends of said tubes in pairs, removable return bends for connecting said first-mentioned return bends, pipes carried by said last-mentioned return bends and projecting into said first-mentioned tubes, whereby a sinuous movement of fluid through said tubes is obtained, and means for securing said last-mentioned return bends in position.

3. A heat exchanger comprising a casing closed at one end, a detachable head for closing the opposite end of saidcasing, tubes secured in and projecting through said head into said casing, the ends of said tubes Within the casing being closed, fixed return bends for connecting the opposite ends of said tubes in pairs, a second set of removable return bends fitting within said first-mentioned return bends, pipes carried by said last-mentioned return bends removable therewith and projecting into said first-mentioned tubes, said pipes being ofless length than said tubes, means for securing said last-mentioned return bends in position, and means through which a heating medium can enter and pass from said casing and surround said first-mentioned tubes.

4. A heat exchanger comprising a casing closed at one end, a removable head for closing the opposite end of said casing, tubes secured in and projecting through said removable head into said casing, the ends of said tubes within the casing be1ng closed, return bends for connecting the opposite ends of said tubes in pairs, removable return bends fitting within said first-mentioned return bends and connecting the same, pipes carried by said lastmentioned return bends and partially projecting, into said first-mentioned tubes, said pipes eing open at their inner ends, means for securing said last-mentioned return bends in position, means through which a heating signature.

FREDERICK E. KEY. 

